1. Field Of The Invention
The apparatus of the present invention relates to oil well tubing, for example, drilling pipe or production casing. More particularly, the present invention relates to an apparatus for engaging the external threads of well casing so as to protect the threads from contact with obstacles while the pipe is being handled.
2. General Background
Protection of the threads of oil well tubing, more particularly, drill pipe or production casing, is a serious and recurring problem in the industry. For purposes of this application, reference to "casing" will encompass any length of tubing used in the drilling or production of oil or gas wells. Casing must be connectedly engaged end to end by threaded connections which must be very secure and be able to protect against leakage of oil or gas under extremely high pressures. Therefore, casing threads are machined to very precise tolerances. However, because the 30 to 60 foot lengths of casing must be handled by machine and moved from racks to be connected to other lengths of casing, it is very difficult to avoid the threaded pin end of the pipe from striking against foreign objects, and the damage to the threads occurring. Of course the slightest deformation of the threads could result in thread malfunctioning.
There have been several patents issued in the art on thread protectors, which patents are addressed in the accompanying prior art statement provided herewith. In addition, one of the co-inventors of the present application has file applications on earlier embodiments, which bear Ser. Nos. 572,266, filed on Aug. 27, 1990, now abandoned, and U.S. application Ser. No. 827,402, filed Jan. 29, 1992, presently pending, both applications incorporated by reference herein. In this application, a co-inventor, Terry Hill, has developed improvements to the current pending application, which improvements greatly simplify and improve the operation of the earlier embodiments.